1. Field of the Invention
This invention relates to an electronic apparatus for being connected to a digital bus of, for example, the IEEE 1394 standard, and a method for setting connection mode to be used when a transmission line is formed between electronic apparatus connected to the digital bus.
2. Description of Related Art
Recently, abundant various digital contents have been become available through the communication media such as broadcasting media and Internet or by way of various recording media such as DVD (digital vide disk). In association with the popularization of digital contents, various home-use digital audio visual apparatus (referred to as digital AV apparatus hereinafter) such as digital broadcast receivers so-called IRD (Intelligent receiver device) having a digital interface, digital television digital monitors, DVTR (digital video tape recorder), and DVD players have been become available.
Various digital AV apparatus having a digital interface are connected through a digital bus in home to form a network to thereby widen the usage range of digital contents that have been become available abundantly and to thereby arrange the easy-to-use environment of digital contents for users.
Various digital interfaces have been available. Among these digital interfaces, the digital serial interface according to IEEE 1394 standard standardized by IEEE (American Electric Electronic Association) that is capable of high rate transfer of digital video signal and digital audio signal that require real time transfer to which IEC 61883-1 standardized standard is applied has attracted attention.
In the present specification, the IEEE 1394 standard digital serial interface to which IEC 61883-1 standardized standard is applied is simply referred to as IEEE 1394 standard digital interface.
In the IEEE 1394 standard digital interface, when a channel (transmission line) between electronic apparatus connected to a digital bus is formed (connection), two connection modes, namely broadcast connection mode and point-to-point connection mode (simply referred to as PtoP connection mode hereinafter), are available.
In the broadcast connection mode, a connection comprises a broadcast-out connection that connects one output plug to one channel and a broadcast-in connection that connects one input plug to one channel.
In the case of the broadcast connection, an electronic apparatus that is a data supplier supplies (broadcast-out) the data to all the electronic apparatus connected to a digital bus, electronic apparatus that are ready to receive the data supply form broadcast-in connection to thereby form a channel between electronic apparatus through which the data is transmitted, and as the result communication through the channel becomes possible.
In the case of the broadcast connection mode, even though there is an electronic apparatus that is transmitting the data already through the broadcast-out connection, sending out of the data from another electronic apparatus that forms broadcast-out connection later is permitted. In this case, sending out of the data from the electronic apparatus that is sending out the data through the broadcast-out connection is stopped, and the data supplied from the electronic apparatus that broadcast-out connects later is transmitted through the digital bus preferentially.
In detail, for example, in the case that an IRD, a digital monitor apparatus, and a DVTR are connected to an IEEE 1394 standard digital bus and the digital monitor apparatus is receiving the digital data from the IRD through a channel formed between the IRD and the digital monitor apparatus according to the broadcast connection, when the DVTR forms connection to a channel according to the broadcast-out connection and sends out the data, sending out of the data from the IRD is stopped and the data sent out from the DVTR is supplied to the digital monitor apparatus.
In this case, for example, without any operation to the digital monitor apparatus entered by a user, the data generated from the DVTR is supplied to the digital monitor apparatus instead of the data generated from the IRD only by instructing playback of the data recorded in a video tape to the DVTR.
Therefore, in the above-mentioned example, when the broadcast connection mode is used, a user can supply the data generated from the target electronic apparatus to the digital monitor apparatus without complex operation performed by a user to the respective IRD, digital monitor apparatus, and DVTR connected to the digital bus.
On the other hand, in the case of the PtoP connection mode, one input plug and one output plug are connected to one channel. Therefore, the data transmission is allowable for electronic apparatus between which a channel has been already formed in the PtoP connection mode, and the data sent out from another electronic apparatus other than the electronic apparatus that have been PtoP connected already cannot be accepted by the network when the data is sent out later.
For example, in the same way as described hereinabove, in the case that the IRD, digital monitor apparatus, and DVTR are in connection through the digital bus, and the digital monitor apparatus is receiving supply of the data sent out from the IRD through a channel formed in the PtoP connection mode, sending out of the data that is sent out from the DVTR through a channel formed in, for example, the broadcast-out connection mode to the digital bus from the DVTR cannot be accepted and the transmission of the data from the IRD to the digital monitor apparatus is maintained unchanged.
The selective usage of the broadcast connection mode and the PtoP connection mode is previously determined for each electronic apparatus having the IEEE 1394 standard digital interface. In other words, which connection mode is used out of the broadcast connection mode and the PtoP connection mode is previously determined according to the predetermined condition for each electronic apparatus.
By the way, as described hereinbefore, the selective usage of the broadcast connection mode and the PtoP connection mode is predetermined for each electronic apparatus having the IEEE 1394 standard digital interface. In the case that a network is formed by connecting a plurality of electronic apparatus having the IEEE 1394 standard to a digital bus, the data could not be transmitted as desired by a user of the network.
For example, as shown in FIG. 10A, in some cases a digital monitor apparatus 1, an IRD 2, a DVTR 3, and DVTR 4, each of which is provided with an IEEE 1394 standard digital interface, are connected to a digital bus to structure an AV apparatus network in home. In FIG. 10B and FIG. 10C, a character 1d denotes a digital input/output terminal of the digital monitor apparatus 1, a character 2d denotes a digital input/output terminal of the IRD 2, a character 3d denotes a digital input/output terminal of the DVTR 3, and a character 4d denotes a digital input/output terminal of the DVTR 4.
In this example, the IRD 2, DVTR 3, and DVTR 4 are connected to the channel of the digital bus of the broadcast-out connection and transmit the data, and also form a channel of the PtoP connection with a requester target apparatus in response to a request from the target apparatus and supply the data only to the requester electronic apparatus.
As shown in FIG. 10B, in the case that the data is being transmitted through a broadcast connected channel from the IRD 2 to the digital monitor apparatus 1, when the DVTR 3 is switched erroneously to the playback mode, transmission of the data from the IRD 2 is stopped, and the data is automatically supplied from the DVTR 3 to the digital monitor apparatus 1 undesirably.
Because in this case the digital television broadcast program received by means of the IRD 2 cannot be viewed, it is required to transmit again the data by means of the broadcast connection from the IRD 2 to the digital bus, for example, the power source of the IRD is supplied again.
Furthermore, because transmission of the data from the IRD 2 is automatically stopped and the data is not supplied from the DVTR 3 to the digital monitor apparatus 1, a scene that is to be seen cannot be seen or the information that is to be obtained cannot be obtained as desired.
As in the case shown in FIG. 10A, as shown in FIG. 11A, in the case that apparatus, each of which has an IEEE 1394 standard digital interface, are connected to form an AV apparatus network, the PtoP connection can cause inconvenience.
For example, as shown in FIG. 11B, while a channel has been formed in the PtoP connection mode between the DVTR 3 and DVTR 4 in response to a request from the DVTR 3 to the DVTR 4 and the data sent out from the DVTR 4 is being recorded in the DVTR 3, the time when a digital television broadcast program that is to be recorded has come and the data from the IRD 2 is wanted to be recorded by means of the DVTR 3, at that time it takes a some considerable time to switch the digital data output apparatus and the data from the IRD 2 is recorded not promptly.
In other words, in the case that the channel is formed in the PtoP connection mode between the DVTR 3 and the DVTR 4 as shown in FIG. 11B, a user instructs a stop of recording processing to the DVTR 3 to release the channel formed in the PtoP connection mode between this apparatus and the DVTR 4 as shown in FIG. 11C (first step). Then, the user sets the DVTR 3 so as to receive the data transmitted from the IRD 2 (second step).
Next, the user turns on a power source to the IRD 2 to set the IRD 2 so as to receive a digital broadcast (third step). Then, the user instructs the DVTR 3 so as to record the data to be supplied (fourth step). Through the first step to fourth step, it becomes possible to duplicate the data to be supplied from the IRD 2 as shown in FIG. 4D.
As described hereinbefore, when an output apparatus formed in the PtoP connection mode that supplies the digital data to other electronic apparatus is to be changed, the operation of the first step to the fourth step is required as described hereinbefore, the operation can require some troublesome work and time. Therefore, in the exemplary case described hereinabove, recording of a target digital television broadcast program from the IRD 2 cannot be started promptly, and the entire target digital broadcast program cannot be recorded.
As the result, even though a plurality of electronic apparatus having an IEEE 1394 standard digital interface are connected through a digital bus to structure an AV apparatus network, an AV apparatus network that is sufficiently convenient for a user cannot be structured in some cases.
By the way, in the case that a plurality of electronic apparatus are connected to the IEEE 1394 standard digital bus and all the electronic apparatus form broadcast connection to the same channel on the IEEE 1394 standard digital bus so as to transmit the data, the data sent out from an electronic apparatus that sends out the data later is allowed to be sent out always. Therefore, in some cases, a plurality of channels of the IEEE 1394 standard digital bus are not used effectively.
To solve the above-mentioned problem, a method has been proposed, in which a communication channel has been set previously for each apparatus to prevent the channel use competition and the channels on the digital bus are used effectively when electronic apparatus connected to the digital bus communicate the data. According to the basic concept of this method, a receiving apparatus for receiving the data is waiting for supply of the data from a channel that has been set previously, and the transmission apparatus for transmitting the data sends out the data to the channel without specifying the receiving apparatus, and it is possible to communicate the data statically.
Furthermore, in this method, the receiving apparatus that is on the side for waiting the data and the transmission apparatus that is on the side for transmitting the data are connected in the above-mentioned broadcast connection mode specified according to the IEEE 1394 standard or IEC 61883-1 standardized standard that are both digital serial interface standard.
Therefore, also in this method, when a transmission apparatus is changed by means of a trigger such as an operation performed by a user, the transmission apparatus that will transmit the data newly works upon the transmission apparatus that is transmitting the data to the channel allocated to the target receiving apparatus to stop the transmission of the data at first, and forms a broadcast-out connection to the channel and transmits the data.
Therefore, the input data is switched without any operation of the receiving apparatus. Furthermore, because the transmission channel is allocated to each apparatus, the different transmission receiver of the data necessarily involves the different channel for transmitting the data, and the competition between a plurality of apparatus for getting one channel is prevented.
However, when the data supplied from a transmission apparatus that forms the broadcast-out connection to the channel allocated to the target receiving apparatus and is transmitting the data as described hereinabove is to be recorded by means of, for example, a recording apparatus such as a DVTR, the recording apparatus forms a connection of the PtoP connection mode additionally to the channel through which the transmission apparatus is sending out the data through the connection formed in the broadcast connection mode.
In the case of recording of the data, a channel is connected in the PtoP connection mode as described hereinabove. The reason is that, because the data to be recorded should be recorded in a recording medium surely differently from the case in which the data is merely monitored, the PtoP connection mode, that protects the channel from being snatched by another electronic apparatus, is used for forming a channel to secure the recording.
However, a channel connected in the PtoP connection mode cannot be used by another electronic apparatus as long as the receiving apparatus to which the channel is connected is not released. Therefore, in some cases that the above-mentioned method is applied to a home network system to which, for example, a DTV and DVTR are connected though the IEEE 1394 standard digital bus, the inconvenience will occur as described herein under.
For example, when the data is to be recorded by a DVTR while a DTV is receiving supply of the data through the broadcast connected channel allocated to this apparatus, the channel formed by the broadcast connection allocated to the DTV is changed to a PtoP connected channel by the DVTR.
In this case, when the DTV is to receive supply of the output data supplied from another apparatus, because the channel allocated to this apparatus is being used as the PtoP connection mode channel by the DVTR, the DTV cannot snatches the channel and the output data supplied to the DTV cannot be switched.
In other words, as shown in FIG. 34, for example, in the case that a channel having the channel No. 63 is allocated to the DTV and, for example, the PtoP connection mode channel is connected between the apparatus K2 and the apparatus K3 to the channel, even if the apparatus K1 is to be connected to the channel in the broadcast connection mode to send out the data, the apparatus K1 cannot be connected to the channel. Furthermore, even if the apparatus K4 is to be connected to the channel in the PtoP connection mode, the apparatus K4 cannot be connected to the channel.
In this case, as long as the PtoP connection mode channel connected between the apparatus K2 and the apparatus K3 is not released, another apparatus cannot sends out the data to the channel. As described hereinbefore, in the case that the broadcast connection mode and the PtoP connection mode are both used, in some cases, the same inconvenience as in the case that all the electronic apparatus connected to the IEEE 1394 standard digital bus use the same channel is caused.
In the case of the broadcast connection mode channel, as described hereinabove, the data to be supplied to a receiving apparatus can be changed only by changing the transmission apparatus that sends out the data to the channel without any operation of the receiving apparatus. On the other hand, in the case of data recording, because the channel is connected in the PtoP connection mode, the data to be supplied to the receiving apparatus that is served as a recording apparatus cannot be changed not only by changing the sender transmission apparatus of the data.
Furthermore, in the case that the communication channel is allocated for each apparatus as described hereinabove, for example, when the data is transmitted and recorded through a channel that a user or a monitor apparatus such as a DTV is not aware of as in the case of timer recording or reservation recording, the user is not aware of the information of the channel through which the data is being transmitted.
For example, in the case that a user sets timer recording because the user will go out but the user cancels the going out and wants to view the program that has been set to be recorded, in some cases the user cannot view immediately the program that is being recorded because the user is not aware of the channel through which the data of the target program is transmitted.
In view of the above, the present invention has been accomplished to eliminate the above-mentioned problem, and it is the object of the present invention to provide an electronic apparatus and a connection mode setting method that are capable of structuring a convenient electronic apparatus network.